Hello,
Yes, I can do this. Everything but HomeKit, mostly because I don't know yet how HomeKit works fromt he point of view of the device, not the Apple machine. So in this bid I'm including you everything else:
1. Alexa skill to control the raspberry with 1 command.
2. A program on a raspberry, connected to the internet, to receive and process said Alexa command, from AWS.
3. The same program will use that command to move a stepper motor, using a stepper control board connected to the PI.
This is just for development, I need the hardware, but you can buy it and send it to me, or I can buy it and ship you the complete, assembled prototype. We'll create an extra milestone for that.
Thanks ,
Sergio